1. Field of Invention
The present invention relates generally to energy management and particularly for computerized power distribution and control.
2. Background of the Invention
According to the Electric Power Research Institute (EPRI), nearly 2.5 billion electrical products containing power supplies are currently in use in the United States, and about 400 to 500 million new power supplies (linear and switching) are sold in the U.S. each year. The total amount of electricity that flows through these power supplies is more than 207 billion kWh/year, or about 6% of the national electric bill.
Power supplies can be located within the devices they are intended to power (internal) or outside of the product in a separate housing. Typical applications that have an external power supply include cordless phones and answering machines, video games, computer speakers, and cordless tools. Most external power supplies are linear power supplies with efficiencies in the range of 30% to 40%.
Typical application of internal power supplies are in personal computer, servers, televisions, monitors, and a wide range of electronic appliances. Most internal power supplies currently in the market are switch-mode power supplies, which have efficiencies in the range of 65% to 70%.
Electronic devices are increasingly being designed and built to use lower voltages at higher currents. Yet, just about every electronic device has to obtain its power from a 120VAC supply (or 220VAC in other countries), because that is what is available from the wall plug. Having to convert from 120VAC to 5V and lower voltages using typical power supplies is very wasteful. Designing for power efficiency is not a priority for power supply manufacturers, because as efficiency increases, the cost of the power supply increases as well.
There are alternative approaches to using individual inefficient power supplies in each device. One approach is to centralize the AC to DC conversion and improve the conversion process using better quality power supplies. Instead of having an AC to DC power supply in each device, there is an advantage to providing a power controller that converts AC into DC power that can be shared across several devices. By consolidating the AC to DC power supplies into the power controller and managing the power distribution, efficiencies of scale come into play. This approach is ideally suited in an enterprise that incorporates a large number of DC devices. It is advantageous for the approach to be comprised of one or more network accessible management control points that provide monitoring and control, one or more distributed power controllers that may consolidate the AC to DC power conversion, and one or more DC controllers that may perform DC to DC conversion of the voltage at or near the final stage of distribution as needed by the end user devices.